1. Field of the Invention
This invention generally relates to ovenized crystal oscillators which provide a stable reference source or frequency in computers or other electronic equipment. Specifically, there is a miniature oscillator assembly for mounting in electronic systems of constrained space requirements.
2. Description of the Related Art
Various devices are well known for providing a reference frequency or source such devices are called oscillators. The oscillator typically has a quartz crystal and may have electronic compensation circuitry to stabilize the output frequency. Ovenized oscillators heat the oscillator to a uniform temperature to obtain a more stable output. The oscillators have been packaged on various support structures and in housings such as metal cans. The size requirements for electronic components are decreasing and at the same time circuit densities are increasing, especially for portable electronics.
Despite the advantages of the prior art oscillators, a current need exists for an ovenized oscillator that has a small package size that minimizes the amount of printed circuit board space used when it is mounted on a printed circuit board.
It is a feature of the invention to provide a miniature ovenized crystal oscillator.
A further feature of the invention is to provide an ovenized oscillator. The oscillator includes a ceramic case that has a cavity. The case has a bottom and a ledge that extends into the cavity. The case has several circuit lines. A substrate is located in the cavity and is supported by the ledge. The substrate has a first and a second surface and several second circuit lines. The second circuit lines are electrically connected to the first circuit lines by a conductive epoxy. A crystal is mounted to the second surface of the substrate and is electrically connected to the second circuit lines. A signal conditioning circuit is mounted to the first surface of the substrate and is electrically connected to the second circuit lines. A heater is mounted to the bottom of the ceramic case and is electrically connected to the first circuit lines. A thermal adhesive is located between the heater and the crystal. The thermal adhesive thermally links the crystal and the heater. A cover is mounted over the cavity to seal the ceramic case.